RE: Opinions Wanted - Lateral Loads Types - Which is more accurate?

Agree with KootK. Both are approximations and it's always important to remember that, but EQ as of right now is much more of a crapshoot. Building performance and even loadings are heavily dependent on building properties (which are highly dependent on modeling assumptions that may or may not be real). Could argue wind is similar, but with wind you're not neglecting a bunch of the load because you're assuming your building will behave a certain way. In earthquakes you are (assuming not doing performance-based design), even for buildings with no special detailing requirements you can use R=3 and eliminate over half your force.

I think the actual input (ground motion) may have an argument for being more accurate but even there you're not comparing apples to apples for code-level inputs because the wind return periods tend to be shorter than seismic.

RE: Opinions Wanted - Lateral Loads Types - Which is more accurate?

Regarding seismic: We don't even know where all the active faults are, or the long term history the many that are known, let alone the trip mechanisms with certainty, and probably never will. In reality, this is really still a very young field.

In my opinion, engineering for seismic forces will always be a crapshoot. There are really just way too many variables.

Mike McCann, PE, SE (WA)

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